What size hole saw do I use?

Orval Fairbairn wrote:

In article ,
Smitty wrote:


When I get to my panel, which isn't going to be soon, I'll probably do
it on the mill. But for those who don't have access to a machine shop, I
wonder why you're talking about hole saws and fly cutters. Don't the
Greenlee type punches work pretty well? You only need a small pilot hole
and a couple of wrenches.


I much prefer the fly cutter, as the Greenlee punches take a lot of
torque and may leave the panel warped in places.


It depends on how sharp the punch is, how thin the metal is and how close
it is to another opening or edge. You can also use them with the panel
insalled in the aircraft.


If you turn the fly cutter slow enough and use a good aluminum cutting
fluid, it works well and safely.

I would also add the fly cutter MUST be sharp and not fed too fast.

If I were going to start a new instrument panel from scratch I would
take a sheet of 1/2" plywood and bolt the panel blank (cut oversize) to
it. I would use a few of the instrument mounting screw holes as well as
holes along the perimeter of the blank. I would use a fly cutter to cut
the holes. When finished I would cut the panel to size.

This would reduce chatter and make clamping of the entire set up easier.

Dan, U.S. Air Force, retired